import java.util.Scanner;
import java.util.InputMismatchException;
public class Exception_1 {
    public static void main(String[] args) {
        System.out.println("202301110038 + 张洪健");
        Scanner scanner = new Scanner(System.in);
        double r = 0;
        boolean inputV = false;
        while(!inputV)
        {
            try {
                r = scanner.nextDouble();
                inputV = true;
            }
            catch (InputMismatchException e)
            {
                System.out.println("输入的数据类型不正确，请重新输入！");
                scanner.nextLine(); // 清除输入缓冲区中的无效数据
            }
        }
        double s = 3.1415926 * r * r;
        System.out.println("圆的面积为: " + s);
    }
}
